look for format parameter in body parameters too

Hi.

I just integrated this module into a project where we had been doing the content negotiation ourselves. It worked perfectly except our codebase expects to be able to request the format through either a POST parameter or through the query string.

So as you can see, I just replaced the manual QUERY_STRING parsing with a call $req->param. I assume you were doing it manually to minimize performance hit if the application doesn't parse the parameters? As a side effect of that, I'm not trying to remove the parameter before it reaches the application.

Anyway, I assume you will probably not like this diff, but wanted to let you know your module is being used and why I'm forking.

Thanks.